Curable composition and method for manufacturing the same

ABSTRACT

A curable composition comprises the following: (A) a branched polymer having an average unit formula (I′):
 
[(R″) 2 SiO 2/2 ] a″ [(CH 2 ═CH)(R″) 2 SiO 1/2 ] b″ [R″SiO 3/2 ] c″ [O 1/2 Si(R″) 2 (CH 2 CH 2 )(R″) 2 SiO 1/2 ] e″ ;
 
(B) a branched organopolysiloxane having at least one silicon-bonded alkenyl group and having a siloxane unit of formula R 4 SiO 3/2 ; (C) an organopolysiloxane having an average unit formula (II) being capped with H:
 
(R 5   2 SiO 2/2 ) f (R 6   3 SiO 1/2 ) g (R 7 SiO 3/2 ) h (SiO 4/2 ) i (CH 2 CH 2 ) j ;
 
and (D) a catalyst, wherein R″, R 4  to R 7 , a″ to c″, e″ and f to j are as defined in the specification.

CROSS-REFERENCES TO RELATED APPLICATIONS

This application is a continuation-in-part application claiming thebenefit of U.S. Ser. No. 13/302,512, filed Nov. 22, 2011, the subjectmatter of which is incorporated herein by reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a curable composition. In particular,the present invention relates to a curable composition, which issuitable for use as the packaging material of electronic components suchas light emitting diodes.

2. Descriptions of the Related Art

Organic resin, due to its properties of high processability, lightweight, low cost and impact resistance etc., has gradually replacedinorganic glass for use as optical components such as optical lens andpackaging materials of electronic components. Recently, due to thedevelopment of light emitting diode techniques (e.g., high brightness,multiple color property etc.), organic silicon resins which have betterheat resistance, water resistance and transparency, have graduallyreplaced epoxy resins for use as the packaging material of electroniccomponents.

An organic silicon resin, such as organopolysiloxane, can be curedthrough alkylation with silicon hydrides. The cured solid product of thealkylation has a high refractive index and transmittance, and can beused as the packaging material of a light emitting diode. For example,JP H8-176447 discloses a curable organopolysiloxane composition,comprising an organopolysiloxane in which each molecule has asilicon-bonded phenyl group and an silicon-bonded alkenyl group, anorganic hydrogen siloxane, and an alkylation catalyst; and JP2003-128922 discloses a curable organopolysiloxane composition,comprising an organopolysiloxane in which each molecule has at least twosilicon-bonded alkenyl groups and a silicon-bonded phenyl group, anorganopolysiloxane in which each molecule has at least twosilicon-bonded H, and an alkylation catalyst. Such curableorganopolysiloxane compositions, due to their high viscosities, havedisadvantages including operation difficulty and poor adhesive propertyto the substrate.

U.S. Pat. No. 7,527,871 B2 discloses a modified curableorganopolysiloxane composition, in comparison to the above prior arts,which comprises a component of a linear organopolysiloxane with at leasttwo silicon-bonded alkenyl groups and at least one aryl group and thus,can provide a cured product with a low viscosity and well adhesiveproperty. However, during the synthesis of the above component, a greatamount of nonreactive residue of methyl phenyl rings is inevitablygenerated for the reaction equilibrium, which will make the surface ofthe cured product obtained from the composition sticky. In addition, anyprocedure used to remove the rings, such as a high-temperaturedistillation, will probably lead to the breakage of the bonding betweenthe phenyl groups and result in the appearance of yellowing.Furthermore, since the added component is a linear organopolysiloxanewith insufficient strength, the cured product will tend to fractureunder a high temperature or a drastic temperature variation.

In view of the above, the present invention provides a curablecomposition without any undesired residue of rings during themanufacturing process. The cured product of the composition hasoutstanding heat resistance, transmittance as well as refractive index,and the yellowing barely occurs during the high temperature curingprocess of the composition. In addition, the ratio or structure of thecomponents contained in the curable composition can be adjusted tosatisfy the demands of a quick curing process and to provide the desiredproperties including superior transmittance, thermal resistance andsurface conditions.

SUMMARY OF THE INVENTION

An objective of the present invention is to provide a curablecomposition comprising:

(A) an organopolysiloxane having at least two silicon-bonded alkenylgroups and having an average unit formula (I):(R¹ ₂SiO_(2/2))_(a)(R²₃SiO_(1/2))_(b)(R³SiO_(3/2))_(c)(SiO_(4/2))_(d)(CH₂CH₂)_(e)  (I);wherein R¹, R² and R³ are independently a substituted or unsubstitutedmono-valent hydrocarbon group, each of R¹ is the same with or differentfrom each other, each of R² is the same with or different from eachother, and a>0, b>0, c≧0, d≧0, and e>0;

(B) a branched organopolysiloxane having at least one silicon-bondedalkenyl group and having a siloxane unit of formula R⁴SiO_(3/2) whereinR⁴ is a substituted or unsubstituted mono-valent hydrocarbon group, andwherein the amount of component (B) is about 1 part by weight to about9900 parts by weight, based on 100 parts by weight of component (A);

(C) an organopolysiloxane having an average unit formula (II) beingcapped with H:(R⁵ ₂SiO_(2/2))_(f)(R⁶₃SiO_(1/2))_(g)(R⁷SiO_(3/2))_(h)(SiO_(4/2))_(i)(CH₂CH₂)_(j)  (II);wherein R⁵, R⁶ and R⁷ are independently H or a substituted orunsubstituted mono-valent hydrocarbon group, wherein each of R⁵ is thesame with or different from each other, each of R⁶ is the same with ordifferent from each other, f>0, g>0, h≧0, i≧0, j≧0, and the amount ofcomponent (C) is about 1 parts by weight to about 300 parts by weight,based on 100 parts by weight of the total amount of components (A) and(B); and

(D) a catalyst.

A further objective of the present invention is to provide a curablecomposition comprising:

(A) a branched polymer having an average unit formula (I′):[(R″)₂SiO_(2/2)]_(a″)[(CH₂═CH)(R″)₂SiO_(1/2)]_(b″)[R″SiO_(3/2)]_(c″)[O_(1/2)Si(R″)₂(CH₂CH₂)(R″)₂SiO_(1/2)]_(e″)  (I′);wherein R″ is a substituted or unsubstituted mono-valent hydrocarbongroup and each of R″ is the same with or different from each other; a″is an integer ranging from 0 to 200; b″ is an integer ranging from 3 to6; c″ is an integer ranging from 1 to 4, and e″ is an integer rangingfrom 2 to 200;

(B) a branched organopolysiloxane having at least one silicon-bondedalkenyl group and having a siloxane unit of formula R⁴SiO_(3/2) whereinR⁴ is a substituted or unsubstituted mono-valent hydrocarbon group, andwherein the amount of component (B) is about 1 part by weight to about9900 parts by weight, based on 100 parts by weight of component (A);

(C) an organopolysiloxane having an average unit formula (II) beingcapped with H:(R⁵ ₂SiO_(2/2))_(f)(R⁶₃SiO_(1/2))_(g)(R⁷SiO_(3/2))_(h)(SiO_(4/2))_(i)(CH₂CH₂)_(j)  (II);wherein R⁵, R⁶ and R⁷ are independently H or a substituted orunsubstituted mono-valent hydrocarbon group, wherein each of R⁵ is thesame or different from each other, each of R⁶ is the same or differentfrom each other, f>0, g>0, h≧0, i≧0, j≧0, and the amount of component(C) is about 1 parts by weight to about 300 parts by weight, based on100 parts by weight of the total amount of components (A) and (B); and

(D) a catalyst.

Another objective of the present invention is to provide a method formanufacturing the above curable composition, comprising performing anaddition reaction of a siloxane having at least two alkenyl groups and asiloxane having at least two H to provide component (A).

The above curable composition according to the invention can be used asthe packaging material of a light emitting diode.

The detailed technology and preferred embodiments implemented for thesubject invention are described in the following paragraphs for peopleskilled in this field to well appreciate the features of the claimedinvention.

DESCRIPTION OF THE PREFERRED EMBODIMENT

Hereinafter, some embodiments of the present invention will be describedin detail. However, the present invention may also be practiced invarious different forms without departing from the spirits of thepresent invention. The scope of the present invention shall not beconsidered to be limited to what is illustrated herein. In addition,unless it is additionally explained, the expressions “a,” “the,” or thelike recited in the specification (especially in the claims) shouldinclude the singular and the plural forms. Furthermore, unless it isadditionally explained, the groups (e.g., a mono-valent hydrocarbongroup, an alkyl group, an aryl group and an alkenyl group) recited inthe specification should include substituted or unsubstituted groups.

One feature of the curable composition of the invention is the use ofcomponent (A). There is no residue of rings with low molecular weight,such as methyl phenyl rings, during the preparation of component (A),therefore the cured product of the curable composition of the inventionhas advantages of including an unsticky surface and rarely generatingyellowing when being cured at a high temperature.

Specifically, the curable composition of the invention comprises:

(A) an organopolysiloxane having at least two silicon-bonded alkenylgroups and having an average unit formula (I):(R¹ ₂SiO_(2/2))_(a)(R²₃SiO_(1/2))_(b)(R³SiO_(3/2))_(c)(SiO_(4/2))_(d)(CH₂CH₂)_(e)  (I);wherein R¹, R² and R³ are independently a substituted or unsubstitutedmono-valent hydrocarbon group, each of R¹ is the same with or differentfrom each other, each of R² is the same with or different from eachother, and a>0, b>0, c≧0, d≧0, and e>0;

(B) a branched organopolysiloxane having at least one silicon-bondedalkenyl group and having a siloxane unit of formula R⁴SiO_(3/2) whereinR⁴ is a substituted or unsubstituted mono-valent hydrocarbon group;

(C) an organopolysiloxane having an average unit formula (II) beingcapped with H:(R⁵ ₂SiO_(2/2))_(f)(R⁶₃SiO_(1/2))_(g)(R⁷SiO_(3/2))_(h)(SiO_(4/2))_(i)(CH₂CH₂)_(j)  (I)wherein R⁵, R⁶ and R⁷ are independently H or a substituted orunsubstituted mono-valent hydrocarbon group, wherein each of R⁵ is thesame with or different from each other, each of R⁶ is the same with ordifferent from each other, f>0, g>0, h≧0, i≧0, and j≧0; and

(D) a catalyst.

Component (A) is an organopolysiloxane having at least twosilicon-bonded alkenyl groups such as alkenyl groups with 2 to 20 carbonatoms, preferably with 2 to 12 carbon atoms, and more preferably with 2to 6 carbon atoms. The examples of alkenyl groups include, but notlimited to, vinyl groups, allyl groups, butenyl groups, pentenyl groupsand hexenyl groups. To keep a low viscosity of the curable composition,the preferred alkenyl groups are vinyl groups with low molecularweights. In addition to the two silicon-bonded alkenyl groups, component(A) further has a substituted or unsubstituted mono-valent hydrocarbongroup. In other words, in the average unit formula of component (A), R¹,R² and R³ are independently substituted or unsubstituted mono-valenthydrocarbon groups. According to the invention, mono-valent hydrocarbongroups include substituted or unsubstituted alkyl groups with 1 to 20carbon atoms, preferably with 1 to 12 carbon atoms, and more preferablywith 1 to 8 carbon atoms, e.g., a methyl group, an ethyl group, a propylgroup, a butyl group, a pentyl group, a hexyl group or a heptyl group;substituted or unsubstituted alkenyl group with 2 to 20 carbon atoms,preferably with 2 to 12 carbon atoms, more preferably with 2 to 6 carbonatoms, e.g., a vinyl group, an allyl group, a butenyl group, a pentenylgroup or a hexenyl group; aryl groups with 6 to 14 carbon atoms, e.g., aphenyl group, a tolyl group, a xylyl group or a naphthyl group;arylalkyl groups with 7 to 15 carbon atoms, e.g., a benzyl group or aphenylethyl group; or halogenated alkyl groups with 1 to 20 carbonatoms, preferably with 1 to 12 carbon atoms, and more preferably with 1to 8 carbon atoms, e.g., 3-chloropropyl group or 3,3,3-trifluoropropylgroup.

According to the invention, there is no special limitation on themolecular weight of component (A). However, in view of the viscosity ofthe whole composition, a, b, c, d and e are preferably as follows:

a is an integer ranging from about 1 to about 200;

b is an integer ranging from about 1 to about 200;

c is an integer ranging from 0 to about 10;

d is an integer ranging from 0 to about 5; and

e is an integer ranging from about 1 to about 100,

wherein, when c+d>0 (i.e., component (A) has a branched-chainstructure), the cured product of the curable composition of theinvention has better mechanical strength.

For example, component (A) may be selected from the following group:

and combinations thereof, wherein each of R is independently an alkylgroup or aryl group, and m and n are independently integers ranging fromabout 1 to about 50; and preferably, each of R is independently aC₁-C₈alkyl group or phenyl group. In some embodiments of the invention,component (A) is

Preferably, component (A) is a branched polymer havingsilalkylenesiloxane units and at least three silicon bonded alkenylterminal groups, which has an average unit formula (I′):[(R″)₂SiO_(2/2)]_(a″)[(CH₂═CH)(R″)₂SiO_(1/2)]_(b″)[R″SiO_(3/2)]_(c″)[O_(1/2)Si(R″)₂(CH₂CH₂)(R″)₂SiO_(1/2)]_(e″)  (I′);wherein R″ is a substituted or unsubstituted mono-valent hydrocarbongroup as defined above and is preferably C₁-C₃ alkyl group or arylgroup, more preferably methyl or phenyl; each of R″ is the same with ordifferent from each other, and preferably, about at least 10 percent bymole of R″ are aryl groups, based on the total amount of R″; a″ is aninteger ranging from 0 to 200, preferably a″ is an integer ranging from1 to 100, and more preferably a″ is an integer ranging from 3 to 50; b″is an integer ranging from 3 to 6, preferably b″ is an integer rangingfrom 3 to 5; c″ is an integer ranging from 1 to 4, preferably c″ is aninteger ranging from 1 to 3, and e″ is an integer ranging from 2 to 200,preferably e″ is an integer ranging from 2 to 100, and more preferablye″ is an integer ranging from 3 to 50.

More preferably, component (A) is a branched polymer selected from:

anda combination thereof,wherein

X is

X′ is

T is

T′ is

R″ is as defined above;

p is an integer ranging from 1 to 4 and each of p is the same with ordifferent from each other;

q is an integer ranging from 1 to 4 and each of q is the same with ordifferent from each other;

r is an integer ranging from 1 to 3, preferably r is 1; and

t is an integer ranging from 0 to 50, preferably an integer ranging from0 to 30, and each of t is the same with or different from each other.

The repeated units, X, T, X′ and T′ can be distributed in a randommanner or in an alternative manner.

Further preferably, component (A) is:

wherein X, T, R″, p and q are as defined above, t₁ and t₂ areindependently an integer ranging from 0 to 30 and t₁+t₂ ranges from 0 to50.

Specifically, component (A) is a branched polymer is selected from:

and a combination thereof, wherein t is as defined above.

It was found that an enhanced hardness, thermal resistance and tensilestrength of a cured composition can be achieved when component (A) is abranched polymer, for example, the branched polymer of the formula(I′-1-a), (I′-1-b), (I′-1-c), (I′-2-a), (I′-2-b), (I′-2-c), (I′-2-d),(I′-2-e), (I′-2-f) or (A-1).

According to the invention, component (A) can be prepared by an additionreaction of a siloxane having at least two alkenyl groups and a siloxanehaving at least two H. During preparation, there is no residue of ringswith low molecular such as methyl phenyl rings, therefore the curedproduct of the curable composition of the invention does not havedisadvantages associated with the residue of rings with low molecular(such as a sticky surface and yellowing) and is thus, very suitable foruse as an optical material. The siloxane having at least two alkenylgroups, for example, can be the one having an average unit formula(III):(R^(1′) ₂SiO_(2/2))_(a′)(R^(2′)₃SiO_(1/2))_(b′)(R³SiO_(3/2))_(c′)(SiO_(4/2))_(d′)  (III);and the siloxane having at least two H can be, for example, one havingan average unit formula (IV):(R^(5′) ₂SiO_(2/2))_(f′)(R^(6′)₃SiO_(1/2))_(g′)(R^(7′)SiO_(3/2))_(h′)(SiO_(4/2))_(i′)  (IV),wherein R^(1′), R^(2′), R^(3′), R^(4′), R^(5′), R^(6′) and R^(7′) areindependently substituted or unsubstituted mono-valent hydrocarbongroups such as alkyl, alkenyl, aryl, arylalkyl or halogenated alkyl asmentioned above; each R¹ is the same as or different from each other;each R^(2′) is the same as or different from each other; each R^(5′) isthe same as or different from each other, each of R^(6′) is the same asor different from each other; and a′>0, b′>0, c′≧0, d′≧0, f′>0, g′>0,h′≧0 and i′≧0.

The structure and molecular weight of component (A) can be adjusted bychoosing different siloxanes having at least two alkenyl groups orsiloxanes having at least two H. For example, the structure of component(A) (e.g., a linear, branched or reticulated structure) can be adjustedby using a linear or branched siloxane having at least two alkenylgroups or a linear or branched siloxane having at least two H. Themolecular weight of component (A) can be adjusted by using siloxanehaving at least two alkenyl groups or siloxane having at least two Hwith different molecular weights, depending on the needs (such as adesired curing rate or mechanical strength).

Based on the total amount of R¹, R² and R³, preferably about 0.1 percentby mole to about 40 percent by mole of R¹, R² and R³ and more preferablyabout 0.3 percent by mole to about 30 percent by mole of R¹, R² and R³are alkenyl groups. The reactivity of component (A) with the othercomponents tends to decrease when the content of alkenyl groups is lowerthan the lower limit of the suggested range or higher than the upperlimit of the suggested range. Furthermore, to increase the refractiveindex of the cured product, preferably at least about 10 percent by moleof R¹, R² and R³ and more preferably at least about 20 percent by moleof R¹, R² and R³ are aryl groups, based on the total amount of R¹, R²and R³.

In some embodiments of the invention, component (A) is prepared bycarrying out the addition reaction by using

or the like as the siloxane having at least two alkenyl groups (n′ is aninteger ranging from about 1 to about 5), and using

or the like as the siloxane having at least two H (m′ is an integerranging from about 1 to about 5) in a molar ratio of about 2:1 to about50:49. For example, component (A)

can be prepared by carrying out an addition reaction ofCH₂═CH(CH₃)₂SiO[(C₆H₅)₂Si]OSi(CH₃)₂CH═CH₂ andH(CH₃)₂SiO[(C₆H₅)₂Si]OSi(CH₃)₂H in a molar ratio of about 10:9.

Component (B) is a branched organopolysiloxane having at least onesilicon-bonded alkenyl group, which is a major component that givesstrength to the cured product of the curable composition of theinvention. The alkenyl group of component (B) may be, for example, thegroups mentioned above, and is preferably a vinyl group with lowmolecular weight. In addition to the silicon-bonded alkenyl group,component (B) further comprises a substituted or unsubstitutedmono-valent hydrocarbon group. In other words, in the average unitformula of component (B), R⁴ can be an alkyl group, an alkenyl group, anaryl group, an arylalkyl group or a halogenated alkyl group as mentionedabove.

According to the embodiment of the invention, the branchedorganopolysiloxane of component (B) has at least one silicon-bondedalkenyl group and at least one silicon-bonded aryl group.

In one specific example of the invention, component (B) has an averageunit formula (V):(R⁴SiO_(3/2))_(k)[(CH₂═CH)(R⁸)₂SiO_(1/2)]_(1-k)  (V),wherein R⁴ is as defined above, R⁸ is a substituted or unsubstitutedmono-valent hydrocarbon group such as an alkyl group, alkenyl group,aryl group, arylalkyl group or halogenated group as mentioned above;each of R⁸ is the same as or different from each other; and k rangesfrom about 0.5 to about 0.95. Preferably, R⁴ is an aryl group or C₁-C₃alkyl, R⁸ is an aryl group or C₁-C₈ alkyl, and k ranges from about 0.6to about 0.9. In some embodiments of the invention, component (B) is(C₆H₅SiO_(3/2))_(0.8)[(CH₂═CH)(CH₃)₂SiO_(1/2)]_(0.2).

In another specific example of the invention, component (B) has anaverage unit formula (VI):(R⁴SiO_(3/2))_(x)(SiO_(4/2))_(y)[(R⁹)₃SiO_(1/2)]_(1-x-y)  (VI),wherein R⁴ is as defined above, R⁹ is a substituted or unsubstitutedmono-valent hydrocarbon group selected from aryl, C₁-C₈ alkyl and C₂-C₈alkenyl, each of R⁹ is the same with or different from each other, x>0,y>0, and x+y ranges from about 0.35 to about 0.85 and wherein about 0.1percent to about 40 percent by mole of R⁹ is C₂-C₈ alkenyl.

Component (B) is preferred to have about 0.1 percent by mole to about 40percent by mole, and more preferably about 0.3 percent by mole to about35 percent by mole, of R⁴ are alkenyl groups, based on the total amountof R⁴. The reactivity of component (B) with other components tends todecrease when the content of alkenyl groups is lower than the lowerlimit of the suggested range or higher than the upper limit of thesuggested range. Furthermore, to increase the refractive index of thecured product, preferably at least about 10 percent by mole, morepreferably at least about 20 percent by mole, of R⁴ are aryl groups,based on the total amount of R⁴.

Among the curable composition of the invention, the amount of component(B) is about 1 part by weight to about 9900 parts by weight, preferablyabout 200 part by weight to about 3000 parts by weight and morepreferably about 300 part by weight to about 2500 parts by weight, basedon 100 parts by weight of component (A). The mechanical strength of thecured product of the curable composition will be insufficient if theamount of component (B) is lower than the lower limit of the suggestedrange. In addition, the cured product of the curable composition willbecome too hard and its applicability scope will be limited if theamount of component (B) is higher than the upper limit of the suggestedrange.

Component (C) is an organopolysiloxane having an average unit formula(II) being capped with H:(R⁵ ₂SiO_(2/2))_(f)(R⁶₃SiO_(1/2))_(g)(R⁷SiO_(3/2))_(h)(SiO_(4/2))_(i)(CH₂CH₂)_(j)  (II),which is the curing agent of the curable composition of the invention.R⁵, R⁶ and R⁷ are independently H or a substituted or unsubstitutedmono-valent hydrocarbon group except alkenyl groups, such as an alkylgroup, an aryl group, an arylalkyl group, or a halogenated alkyl groupas mentioned above. Furthermore, to increase the refractive index of thecured product, based on the total amount of R⁵, R⁶ and R⁷, preferablyabout 0.1 percent by mole to about 50 percent by mole of R⁵, R⁶ and R⁷are H and at least about 5 percent by mole are aryl groups, and morepreferably about 5 percent by mole to about 35 percent by mole of R⁵, R⁶and R⁷ are H and at least about 10 percent by mole are aryl groups.

Furthermore, according to the invention, there is no special limitationon the molecular weight of component (C). However, in view of theviscosity of the whole composition, f, g, h, i and j are preferably asfollows:

f is an integer ranging from about 1 to about 50;

g is an integer ranging from about 1 to about 50;

h is an integer ranging from 0 to about 10;

i is an integer ranging from 0 to about 5; and

j is an integer ranging from 0 to about 30.

Component (C) may be selected from the following group:

and combinations thereof,wherein each R′ is independently an alkyl group or aryl group, and m″and n″ are independently an integer ranging from 0 to about 30; andpreferably, each R′ is independently a C₁-C₈alkyl group or a phenylgroup, and m″ and n″ are independently an integer ranging from 0 toabout 15. In some embodiments of the invention, component (C) isH(CH₃)₂SiO[(C₆H₅)₂Si]OSi(CH₃)₂H,

or a combination thereof.

Among the curable compositions of the invention, the amount of component(C) is about 1 part by weight to about 300 parts by weight, preferablyabout 10 parts by weight to about 250 parts by weight and morepreferably about 15 parts by weight to about 200 parts by weight, basedon 100 parts by weight of the total amount of components (A) and (B). Ifthe amount of component (C) is lower than the lower limit of thesuggested range, the composition may not be cured sufficiently; and ifthe amount of component (C) is higher than the upper limit of thesuggested range, the heat resistance of the cured product of thecomposition tends to decrease.

Component (D) is a catalyst to promote the curing of the composition,which catalyzes the reaction between the alkenyl groups of components(A) and (B) and the silicon-bonded H of component (C). The catalyst maybe selected from the following group: Pt, Rh, Pd, compounds andcomplexes of the above, and combinations thereof, and is preferably a Ptcatalyst. The embodiments of the Pt catalyst are, for example, Ptpowders, chloroplatinic acid, an alcohol solution of chloroplatinicacid, Pt/alkenyl-siloxane complexes, Pt/alkene complexes and Pt/carbonylcomplexes, wherein the Pt/alkenyl-siloxane complexes are preferred.Furthermore, there is no limitation on the amount of component (D) aslong as component (D) can provide the desired promoting effect for thecuring of the composition. Generally, the amount of component (D) isabout 0.01 ppm to about 500 ppm, and preferably about 0.01 ppm to about100 ppm, based on the metal amount contained in component (D). If theamount of component (D) is lower than the lower limit of the suggestedrange, the catalyst cannot provide the desired catalytic effect and thecomposition may not be cured sufficiently; and if the amount ofcomponent (D) is higher than the upper limit of the suggested range, thecured product of the composition may be provided with undesired color.

Furthermore, under the premise of not damaging the objective of theinvention, other curing agents and/or additives (e.g., adhesionpromoters, inorganic fillers, heat stabilizers, pigments, flameretardants and solvents) may be added into the curable composition ofthe invention. The relevant disclosure and specific embodiments canrefer to U.S. Pat. No. 7,527,871 B2, and the full content of which isincorporated herein for reference.

The curable composition of the invention can be cured to provide a curedproduct with a low viscosity, good operation ability, a high refractiveindex (>1.50), and a high transmittance without yellowing. Thus, thecurable composition of the invention is suitable for use as a packagingmaterial of light emitting diodes.

The present invention further provides a method for manufacturing theabove curable composition. The method comprises an addition reaction ofa siloxane having at least two alkenyl groups and a siloxane having atleast two H to provide component (A); and mixing component (A) with theabove components (B), (C) and (D) and other desired additives. Personswith ordinary skill in the art can easily comprehend and carry out themethod after reviewing the disclosure of the specification and there isno need to further describes the detailed process of the method here.

The present invention further relates to a semiconductor device, whichcomprises semiconductor elements. The semiconductor elements are coatedwith a cured product of the foregoing curable composition. In apreferable aspect, the semiconductor elements are light emitting diodesor light sensors.

The present invention will be further illustrated by the embodimentshereinafter,

wherein the measuring instruments and methods are respectively asfollows:

<Refractive Index of the Cured Product>

The refractive index of the sample was measured by Abbe refractometer ofATAGO company (light source: a visible light with a wavelength of 589nm) at 25° C.

<Transmittance of the Cured Product>

The transmittance of the sample was measured by Lambda 650 instrument ofPerkin Elmer company (light source: a visible light with a wavelength of450 nm; optical path length: about 1 mm).

<Hardness of the Cured Product>

The hardness of the sample was measured by Shore durometer (model no.:GS-720N and GS-709G) of the TECLOCK company.

<Tensile Strength and Elongation of the Cured Product>

The tensile strength and the elongation were measured according to JISK6251. Each cured body having the shape of dumbbell-type specimen No. 3was produced by heating 80° C./1 h and 150° C./4 h inhot-air-circulation oven.

EXAMPLES Preparation of Component (A)

1.0 mol of CH₂═CH(CH₃)₂SiO[(C₆H₅)₂Si]OSi(CH₃)₂CH═CH₂ was mixed with 0.9mol of H(CH₃)₂SiO[(C₆H₅)₂Si]OSi(CH₃)₂H and a Pt metal catalyst was addedinto the resultant mixture to carry out an addition reaction. Component(A) (viscosity: 8,147 mPa·sec) was obtained:

Preparation of Component (A-1)

0.3 mol of CH₂═CH(CH₃)₂SiO[(C₆H₅)₂Si]OSi(CH₃)₂CH═CH₂ was mixed with 0.1mol of H(CH₃)₂SiO[(C₆H₅)SiOSi(CH₃)₂H]OSi(CH₃)₂H and a Pt metal catalystwas added into the resultant mixture to carry out an addition reaction.Component (A-1) (viscosity: 248 mPa·sec) was obtained:

Preparation of Component (A-2)

0.9 mol of CH₂═CH(CH₃)₂SiO[(C₆H₅)₂Si]OSi(CH₃)₂CH═CH₂ was mixed with 1.0mol of H(CH₃)₂SiO[(C₆H₅)₂Si]OSi(CH₃)₂H and a Pt metal catalyst was addedinto the resultant mixture to carry out an addition reaction. After thereaction, 0.2 mol ofCH₂═CH(CH₃)₂SiO[(C₆H₅)SiOSi(CH₃)₂CH═CH₂]OSi(CH₃)₂CH═CH₂ was added intothe product mixture to carry out an addition reaction. Component (A-2)(viscosity: 7,594 mPa·sec) was obtained:

Preparation of Component (A-3)

2 mole of H(CH₃)₂SiO[(C₆H₅)₂Si]OSi(CH₃)₂H was mixed with 1 mole ofCH₂═CH(CH₃)₂SiO[(C₆H₅)₂Si]OSi(CH₃)₂CH═CH₂ and a Pt metal catalyst wasadded into the resultant mixture to carry out an addition reaction. Thereaction was continued with adding 0.33 mole ofCH₂═CH(CH₃)₂SiO[(C₆H₅)SiOSi(CH₃)₂CH═CH₂]OSi(CH₃)₂CH═CH₂ and 1.0 mole ofCH₂═CH(CH₃)₂SiO[(C₆H₅)₂Si]OSi(CH₃)₂CH═CH₂ in sequence. Component (A-3)(viscosity: 2361 mPa·sec) was obtained:

Preparation of Component (A-4)

2 mole of H(CH₃)₂SiO[(C₆H₅)(CH₃)Si]OSi(CH₃)₂H was mixed with 1 mole ofCH₂═CH(CH₃)₂SiO[(C₆H₅)(CH₃)Si]OSi(CH₃)₂CH═CH₂ and a Pt metal catalystwas added into the resultant mixture to carry out an addition reaction.The reaction was continued with adding 0.33 mole ofCH₂═CH(CH₃)₂SiO[(C₆H₅)SiOSi(CH₃)₂CH═CH₂]OSi(CH₃)₂CH═CH₂ and 1 mole ofCH₂═CH(CH₃)₂SiO[(C₆H₅)(CH₃)Si]OSi(CH₃)₂CH═CH₂ in sequence. Component(A-4) (viscosity: 276 mPa·sec) was obtained:

Preparation of Component (A-5)

2 mole of H(CH₃)₂SiO[(C₆H₅)₂SiOSi(C₆H₅)₂]OSi(CH₃)₂H was mixed with 1mole of CH₂═CH(CH₃)₂SiO[(C₆H₅)(CH₃)Si]OSi(CH₃)₂CH═CH₂ and a Pt metalcatalyst was added into the resultant mixture to carry out an additionreaction. The reaction was continued with adding 0.33 mole ofCH₂═CH(CH₃)₂SiO[(C₆H₅)SiOSi(CH₃)₂CH═CH₂]OSi(CH₃)₂CH═CH₂ and 1 mole ofCH₂═CH(CH₃)₂SiO[(C₆H₅)(CH₃)Si]OSi(CH₃)₂CH═CH₂ in sequence. Component(A-5) (viscosity: 2568 mPa·sec) was obtained:

Preparation of Component (A-6)

3 mole of H(CH₃)₂SiO[(C₆H₅)₂Si]OSi(CH₃)₂H was mixed with 2 mole ofCH₂═CH(CH₃)₂SiO[(C₆H₅)₂Si]OSi(CH₃)₂CH═CH₂ and a Pt metal catalyst wasadded into the resultant mixture to carry out an addition reaction. Thereaction was continued with adding 0.33 mole ofCH₂═CH(CH₃)₂SiO[(C₆H₅)SiOSi(CH₃)₂CH═CH₂]OSi(CH₃)₂CH═CH₂ and 1 mole ofCH₂═CH(CH₃)₂SiO[(C₆H₅)₂Si]OSi(CH₃)₂CH═CH₂ in sequence. Component (A-6)(viscosity: 4620 mPa·sec) was obtained:

Preparation of Component (C-1)

0.9 mol of CH₂═CH(CH₃)₂SiO[(C₆H₅)₂Si]OSi(CH₃)₂CH═CH₂ was mixed with 1.0mol of H(CH₃)₂SiO[(C₆H₅)₂Si]OSi(CH₃)₂H and a Pt metal catalyst was addedinto the resultant mixture to carry out an addition reaction. Component(C-1) (viscosity: 5,758 mPa·sec) was obtained:

Preparation of Component (C-2)

0.3 mol of H(CH₃)₂SiO[(C₆H₅)₂Si]OSi(CH₃)₂H was mixed with 0.1 mol ofCH₂═CH(CH₃)₂SiO[(C₆H₅)SiOSi(CH₃)₂CH═CH₂]OSi(CH₃)₂CH═CH₂ and a Pt metalcatalyst was added into the resultant mixture to carry out an additionreaction. Component (C-2) (viscosity: 372 mPa·sec) was obtained:

Preparation of Component (C-3)

1.0 mol of CH₂═CH(CH₃)₂SiO[(C₆H₅)₂Si]OSi(CH₃)₂CH═CH₂ was mixed with 0.9mol of H(CH₃)₂SiO[(C₆H₅)₂Si]OSi(CH₃)₂H and a Pt metal catalyst was addedinto the resultant mixture to carry out an addition reaction. After thereaction, 0.2 mol of H(CH₃)₂SiO[(C₆H₅)SiOSi(CH₃)₂H]OSi(CH₃)₂H was addedinto the mixture to carry out an addition reaction. Component (C-3)(viscosity: 7,512 mPa·sec) was obtained:

Example 1

The obtained component (A) was mixed with the following components toprepare a curable composition 1 (viscosity: 2,824 mPa·sec):

component (A): 7 parts by weight;

component (B): an organopolysiloxane (65 parts by weight; solid at 25°C.) with an average molecular weight of 1,729, a silicon-bonded phenylgroup content of 57% by mole, a silicon-bonded vinyl group content of4.07% by weight, and the following structure:(C₆H₅SiO_(3/2))_(0.8)[(CH₂═CH)(CH₃)₂SiO_(1/2)]_(0.2);

component (C): an organopolysiloxane (24 parts by weight) with thefollowing structure:H(CH₃)₂SiO[(C₆H₅)₂Si]OSi(CH₃)₂H;

component (D): a complex of Pt and1,3-divinyl-1,1,3,3-tetramethoxyldisiloxane, used in an amount such thatthe concentration of Pt was about 1.5 ppm; and

component (E): 1-acetenyl-1-cyclohexanol (0.05 parts by weight) foruniformly mixing the components.

Example 2

The preparation procedures of Example 1 were repeated except forchanging the amounts of components (A), (B) and (C) as follows (theamounts of the rest of the components were not changed). Curablecomposition 2 (viscosity: 3,218 mPa·sec) was obtained.

component (A): 13 parts by weight;

component (B): 60 parts by weight; and

component (C): 23 parts by weight.

Example 3

The preparation procedures of Example 1 were repeated except forchanging the amounts of components (A), (B) and (C) as follows (theamounts of the rest of the components were not changed). Curablecomposition 3 (viscosity: 3,684 mPa·sec) was obtained.

component (A): 21 parts by weight;

component (B): 53 parts by weight; and

component (C): 22 parts by weight.

Comparative Example 4

The following components were mixed to obtain curable composition 4(viscosity: 2,832 mPa·sec).

component (A): a linear methyl phenyl organopolysiloxane (25 parts byweight; viscosity: 1,675 mPa·sec) capped with dimethyl vinyl groups,with a silicon-bonded phenyl group content of 49.8% by mole and asilicon-bonded vinyl group content of 1.12% by weight;

component (B): an organopolysiloxane (53 parts by weight; solid at 25°C.) with a weight average molecular weight of 1,729, a silicon-bondedphenyl group content of 57% by mole, a silicon-bonded vinyl groupcontent of 4.07% by weight, and the following structure:(C₆H₅SiO_(3/2))_(0.8)[(CH₂═CH)(CH₃)₂SiO_(1/2)]_(0.2);

component (C): an organopolysiloxane (21 parts by weight) with thefollowing structure:H(CH₃)₂SiO[(C₆H₅)₂Si]OSi(CH₃)₂H;

component (D): a complex of Pt and1,3-divinyl-1,1,3,3-tetramethoxyldisiloxane, used in an amount such thatthe concentration of Pt was about 1.5 ppm; and

component (E): 1-acetenyl-1-cyclohexanol (0.05 parts by weight) foruniformly mixing the components.

Example 5

The following components were mixed to obtain a curable composition 5(viscosity: 2,720 mPa·sec):

component (A): 7.1 parts by weight;

component (B-1): an organopolysiloxane (66.6 parts by weight; solid at25° C.) with a weight average molecular weight of 1,312, asilicon-bonded phenyl group content of 52.7% by mole, a silicon-bondedvinyl group content of 4.72% by weight, and the following structure:(C₆H₅SiO_(3/2))_(0.77)[(CH₂═CH)(CH₃)₂SiO_(1/2)]_(0.23);

component (C): an organopolysiloxane (24.2 parts by weight) with thefollowing structure:H(CH₃)₂SiO[(C₆H₅)₂Si]OSi(CH₃)₂H;

component (D): a complex of Pt and1,3-divinyl-1,1,3,3-tetramethoxyldisiloxane, used in an amount such thatthe concentration of Pt was about 1.5 ppm; and component (E):1-acetenyl-1-cyclohexanol (0.05 parts by weight) for uniformly mixingthe components.

Example 6

The following components were mixed to obtain a curable composition 6(viscosity: 2,389 mPa·sec):

component (A): 12.9 parts by weight;

component (A-1): 1.9 parts by weight;

component (B-1): an organopolysiloxane (61.0 parts by weight; solid at25° C.) with a weight average molecular weight of 1,312, asilicon-bonded phenyl group content of 52.7% by mole, a silicon-bondedvinyl group content of 4.72% by weight, and the following structure:(C₆H₅SiO_(3/2))_(0.77)[(CH₂═CH)(CH₃)₂SiO_(1/2)]_(0.23);

component (C): an organopolysiloxane (22.2 parts by weight) with thefollowing structure:H(CH₃)₂SiO[(C₆H₅)₂Si]OSi(CH₃)₂H;

component (D): a complex of Pt and1,3-divinyl-1,1,3,3-tetramethoxyldisiloxane, used in an amount such thatthe concentration of Pt was about 1.5 ppm; and

component (E): 1-acetenyl-1-cyclohexanol (0.05 parts by weight) foruniformly mixing the components.

Example 7

The following components were mixed to obtain a curable composition 7(viscosity: 2,361 mPa·sec):

component (A-2): 13.1 parts by weight;

component (B-1): an organopolysiloxane (61.8 parts by weight; solid at25° C.) with an average molecular weight of 1,312, a silicon-bondedphenyl group content of 52.7% by mole, a silicon-bonded vinyl groupcontent of 4.72% by weight, and the following structure:(C₆H₅SiO_(3/2))_(0.77)[(CH₂═CH)(CH₃)₂SiO_(1/2)]_(0.23);

component (C): an organopolysiloxane (22.5 parts by weight) with thefollowing structure:H(CH₃)₂SiO[(C₆H₅)₂Si]OSi(CH₃)₂H;

component (D): a complex of Pt and1,3-divinyl-1,1,3,3-tetramethoxyldisiloxane, used in an amount such thatthe concentration of Pt was about 1.5 ppm; and

component (E): 1-acetenyl-1-cyclohexanol (0.05 parts by weight) foruniformly mixing the components.

Example 8

The following components were mixed to obtain a curable composition 8(viscosity: 2,589 mPa·sec):

component (A): 12.9 parts by weight;

component (B-1): an organopolysiloxane (61.0 parts by weight; solid at25° C.) with an average molecular weight of 1,312, a silicon-bondedphenyl group content of 52.7% by mole, a silicon-bonded vinyl groupcontent of 4.72% by weight, and the following structure:(C₆H₅SiO_(3/2))_(0.77)[(CH₂═CH)(CH₃)₂SiO_(1/2)]_(0.23);

component (C): an organopolysiloxane (22.2 parts by weight) with thefollowing structure:H(CH₃)₂SiO[(C₆H₅)₂Si]OSi(CH₃)₂H;

component (C-1): 1.9 parts by weight;

component (D): a complex of Pt and1,3-divinyl-1,1,3,3-tetramethoxyldisiloxane, used in an amount such thatthe concentration of Pt was about 1.5 ppm; and

component (E): 1-acetenyl-1-cyclohexanol (0.05 parts by weight) foruniformly mixing the components.

Example 9

The following components were mixed to obtain a curable composition 9(viscosity: 2,665 mPa·sec):

component (A): 12.9 parts by weight;

component (B-1): an organopolysiloxane (61.0 parts by weight; solid at25° C.) with an average molecular weight of 1,312, a silicon-bondedphenyl group content of 52.7% by mole, a silicon-bonded vinyl groupcontent of 4.72% by weight, and the following structure:(C₆H₅SiO_(3/2))_(0.77)[(CH₂═CH)(CH₃)₂SiO_(1/2)]_(0.23);

component (C): an organopolysiloxane (22.2 parts by weight) with thefollowing structure:H(CH₃)₂SiO[(C₆H₅)₂Si]OSi(CH₃)₂H;

component (C-2): 1.9 parts by weight;

component (D): a complex of Pt and1,3-divinyl-1,1,3,3-tetramethoxyldisiloxane, used in an amount such thatthe concentration of Pt was about 1.5 ppm; and

component (E): 1-acetenyl-1-cyclohexanol (0.05 parts by weight) foruniformly mixing the components.

Example 10

The following components were mixed to obtain a curable composition 10(viscosity: 2,720 mPa·sec):

component (A): 12.9 parts by weight;

component (B-1): an organopolysiloxane (61.0 parts by weight; solid at25° C.) with an average molecular weight of 1,312, a silicon-bondedphenyl group content of 52.7% by mole, a silicon-bonded vinyl groupcontent of 4.72% by weight, and the following structure:(C₆H₅SiO_(3/2))_(0.77)[(CH₂═CH)(CH₃)₂SiO_(1/2)]_(0.23);

component (C): an organopolysiloxane (22.2 parts by weight) with thefollowing structure:H(CH₃)₂SiO[(C₆H₅)₂Si]OSi(CH₃)₂H;

component (C-3): 1.9 parts by weight;

component (D): a complex of Pt and1,3-divinyl-1,1,3,3-tetramethoxyldisiloxane, used in an amount such thatthe concentration of Pt was about 1.5 ppm; and

component (E): 1-acetenyl-1-cyclohexanol (0.05 parts by weight) foruniformly mixing the components.

[Cured Product Test]

Curable compositions 1-10 prepared by Examples 1-3 and 5-10 andComparative example 4 were placed in an oven (80° C.) with hot-aircirculation respectively for 1 hour. The temperature of the oven wasthen raised to 150° C. and maintained for 4 hours to obtain curedproducts. The properties of the obtained cured products were measured bythe above measuring method. The results were shown in Table 1-1, Table1-2, and Table 1-3.

TABLE 1-1 Compara- Exam- Exam- Exam- tive exam- Property ple 1 ple 2 ple3 ple 4 Refractive index 1.53 1.54 1.53 1.53 Appearance trans- trans-trans- trans- parent parent parent parent Transmittance 98% 98% 98% 95%Hardness (Shore 20   60   40   20   hardness D) Stickiness of unstickyunsticky unsticky sticky the surface Transmittance 92% 93% 93% 73%(after being treated at 200° C. for 72 hours)

TABLE 1-2 Exam- Exam- Exam- Property ple 5 ple 6 ple 7 Refractive index1.53 1.53 1.53 Appearance trans- trans- trans- parent parent parentTransmittance 98% 98% 98% Hardness (Shore 75   56   53   hardness A)Transmittance 91% 91% 91% (after being treated at 200° C. for 72 hours)

TABLE 1-3 Exam- Exam- Exam- Property ple 8 ple 9 ple 10 Refractive index1.53 1.53 1.53 Appearance trans- trans- trans- parent parent parentTransmittance 98% 98% 98% Hardness (Shore 65   52   54   hardness A)Transmittance 91% 91% 91% (after being treated at 200° C. for 72 hours)

As shown in Table 1-1, Table 1-2 and Table 1-3, the cured products fromthe curable compositions of the invention (Examples 1-3 and 5-10) haverefractive indexes comparable with that of the cured product from thecurable composition of the prior art (Comparative example 4), withouthaving a sticky surface. In addition, after being treated at 200° C. for72 hours, the transmittances and appearances of the cured products fromthe curable compositions of the invention almost remain unchanged. Incontrast, the transmittance of the cured product from the curablecomposition of the prior art decreases significantly. It can be seenthat the cured product provided by the invention has better heatresistance and thus, much more suitable for use in semiconductorelements such as high efficiency light emitting diodes. Furthermore, itcan be seen from the hardness results of Examples 1-3 and 5-10 that thehardness of cured products can be changed by simply adjusting thecomponents and component ratios of the curable composition of thepresent invention, without damaging the excellent fraction rate andtransmittance thereof, and thus the applicability of the product israised.

Given the above, the curable composition of the invention can be curedto provide a product with a high refractive index, high transmittance,unsticky surface and good heat resistance and is thus, very suitable foruse as an optical material such as the packaging material of lightemitting diodes. In addition, the applicability of the curablecomposition of the invention is more extensive because the properties ofthe cured product can be simply adjusted by regulating the ratio of thecomponents of the composition.

Example 11

The following components were mixed to obtain a curable composition 11(viscosity: 4,327 mPa·sec):

component (A-3): 19 parts by weight;

component (B): an organopolysiloxane (60 parts by weight; solid at 25°C.) with an average molecular weight of 1,729, a silicon-bonded phenylgroup content of 57% by mole, a silicon-bonded vinyl group content of4.07% by weight, and the following structure:(C₆H₅SiO_(3/2))_(0.8)[(CH₂═CH)(CH₃)₂SiO_(1/2)]_(0.2)

component (C): an organopolysiloxane (21 parts by weight) with thefollowing structure:H(CH₃)₂SiO[(C₆H₅)₂Si]OSi(CH₃)₂H

component (D): a complex of Pt and1,1-divinyl-1,1,3,3-tetramethylsiloxane, used in an amount such that theconcentration of Pt was about 1.5 ppm; and

component (E): 1-ethynyl-1-cyclohexanol (0.05 parts by weight) foruniformly mixing the components.

Example 12

The following components were mixed to obtain a curable composition 12(viscosity: 4,591 mPa·sec):

component (A-5): 19 parts by weight;

component (B): an organopolysiloxane (60 parts by weight; solid at 25°C.) with an average molecular weight of 1,729, a silicon-bonded phenylgroup content of 57% by mole, a silicon-bonded vinyl group content of4.07% by weight, and the following structure:(C₆H₅SiO_(3/2))_(0.8)[(CH₂═CH)(CH₃)₂SiO_(1/2)]_(0.2)

component (C): an organopolysiloxane (21 parts by weight) with thefollowing structure:H(CH₃)₂SiO[(C₆H₅)₂Si]OSi(CH₃)₂H

component (D): a complex of Pt and1,1-divinyl-1,1,3,3-tetramethylsiloxane, used in an amount such that theconcentration of Pt was about 1.5 ppm; and

component (E): 1-ethynyl-1-cyclohexanol (0.05 parts by weight) foruniformly mixing the components.

Example 13

The following components were mixed to obtain a curable composition 13(viscosity: 5,147 mPa·sec):

component (A-6): 18 parts by weight;

component (B): an organopolysiloxane (59 parts by weight; solid at 25°C.) with an average molecular weight of 1,729, a silicon-bonded phenylgroup content of 57% by mole, a silicon-bonded vinyl group content of4.07% by weight, and the following structure:(C₆H₅SiO_(3/2))_(0.8)[(CH₂═CH)(CH₃)₂SiO_(1/2)]_(0.2)

component (C): an organopolysiloxane (21 parts by weight) with thefollowing structure:H(CH₃)₂SiO[(C₆H₅)₂Si]OSi(CH₃)₂H

component (D): a complex of Pt and1,1-divinyl-1,1,3,3-tetramethylsiloxane, used in an amount such that theconcentration of Pt was about 1.5 ppm; and

component (E): 1-ethynyl-1-cyclohexanol (0.05 parts by weight) foruniformly mixing the components.

Example 14

The following components were mixed to obtain a curable composition 14(viscosity: 5,347 mPa·sec):

component (A-4): 20 parts by weight;

component (B-2): an organopolysiloxane (58 parts by weight; solid at 25°C.) with an average molecular weight of 1,800, a silicon-bonded phenylgroup content of 22% by mole, a silicon-bonded vinyl group content of5.62% by weight, and the following structure:(C₆H₅SiO_(3/2))_(0.313)(SiO_(4/2))_(0.312)[(CH₂═CH)(CH₃)₂SiO_(1/2)]_(0.375)

component (C): an organopolysiloxane (22 parts by weight) with thefollowing structure:H(CH₃)₂SiO[(C₆H₅)₂Si]OSi(CH₃)₂H

component (D): a complex of Pt and1,1-divinyl-1,1,3,3-tetramethylsiloxane, used in an amount such that theconcentration of Pt was about 1.5 ppm; and

component (E): 1-ethynyl-1-cyclohexanol (0.05 parts by weight) foruniformly mixing the components.

Comparative Example 15

The following components were mixed to obtain a curable composition 15(viscosity: 4,900 mPa·sec):

linear component (A): 18 parts by weight with the following structure:

component (B): an organopolysiloxane (59 parts by weight; solid at 25°C.) with an average molecular weight of 1,729, a silicon-bonded phenylgroup content of 57% by mole, a silicon-bonded vinyl group content of4.07% by weight, and the following structure:(C₆H₅SiO_(3/2))_(0.8)[(CH₂═CH)(CH₃)₂SiO_(1/2)]_(0.2)

component (C): an organopolysiloxane (21 parts by weight) with thefollowing structure:H(CH₃)₂SiO[(C₆H₅)₂Si]OSi(CH₃)₂H

component (D): a complex of Pt and1,1-divinyl-1,1,3,3-tetramethylsiloxane, used in an amount such that theconcentration of Pt was about 1.5 ppm; and

component (E): 1-ethynyl-1-cyclohexanol (0.05 parts by weight) foruniformly mixing the components.

[Cured Product Test]

Curable compositions prepared by Examples 11 to 14 and Comparativeexample 15 were placed in an oven (80° C.) with hot-air circulationrespectively for 1 hour. The temperature of the oven was then raised to150° C. and maintained for 4 hours to obtain cured products. Theproperties of the obtained cured products were measured by the abovemeasuring method. The results were shown in Table 1-4.

TABLE 1-4 Compara- Exam- Exam- Exam- Exam- tive Exam- Property ple 11ple 12 ple 13 ple 14 ple 15 Refractive index 1.53 1.54 1.53 1.48 1.53Appearance trans- trans- trans- trans- trans- parent parent parentparent parent Transmittance 98% 98% 98% 98% 98% Hardness (Shore 35 42 3731 25 hardness D) Stickiness of smooth smooth smooth smooth smooth thesurface and and and and and unsticky unsticky unsticky unsticky unstickyTransmittance 93% 93% 93% 96% 92% (after being treated at 200° C. for 72hours) Tensile Strength 4.8 6.0 5.0 4.5 3.5 (MPa) Elongation (%) 166 160170 165 175

The branched components (A-3), (A-5), (A-6) and (A-4) were respectivelyused in the curable compositions of Examples 11-14 while the linearcomponent (A) was used in the curable composition of Comparative Example15. As shown in Table 1-4, the cured products from the curablecompositions of Examples 11-14 have superior hardness, thermalresistance and tensile strength than the cured product from the curablecomposition of Comparative Example 15. Accordingly, the cured productsfrom the curable compositions including branched polymers as thecomponent (A) exhibit better mechanical strength. Furthermore,comparable elongation and superior tensile strength provide the curedproducts with superior toughness, such that the cured products are ableto resist stronger external forces and bear higher stress. For example,when the cured products are used as packaging materials of electroniccomponents such as light emitting diodes (LED), the cured products willbe exposed in the air and inevitably absorb moisture, which results indeformation or fracture of the packaging materials since hightemperature or a drastic temperature variation, generated during chipwelding, causes thermal expansion of water. Therefore, a curablecomposition including a branched polymer (A) presents outstandingeffects than that including a linear one.

The above disclosure is related to the detailed technical contents andinventive features thereof. People skilled in this field may proceedwith a variety of modifications and replacements based on thedisclosures and suggestions of the invention as described withoutdeparting from the characteristics thereof. Nevertheless, although suchmodifications and replacements are not fully disclosed in the abovedescriptions, they have substantially been covered in the followingclaims as appended.

What is claimed is:
 1. A curable composition comprising: (A) a branchedpolymer having an average unit formula (I′):[(R″)₂SiO_(2/2)]_(a″)[(CH₂═CH)(R″)₂SiO_(1/2)]_(b″)[R″SiO_(3/2)]_(c″)[O_(1/2)Si(R″)₂(CH₂CH₂)(R″)₂SiO_(1/2)]_(e″)  (I′),wherein R″ is a substituted or unsubstituted mono-valent hydrocarbongroup, each of R″ is the same with or different from each other, a″ isan integer ranging from 0 to 200, b″ is an integer ranging from 3 to 6,c″ is an integer ranging from 1 to 4, and e″ is an integer ranging from2 to 200; (B) a branched organopolysiloxane having at least onesilicon-bonded alkenyl group and having a siloxane unit of formulaR⁴SiO_(3/2) wherein R⁴ is a substituted or unsubstituted mono-valenthydrocarbon group, and wherein the amount of component (B) is about 1part by weight to about 9900 parts by weight, based on 100 parts byweight of component (A); (C) an organopolysiloxane having an averageunit formula (II) being capped with H:(R⁵ ₂SiO_(2/2))_(f)(R⁶₃SiO_(1/2))_(g)(R⁷SiO_(3/2))_(h)(SiO_(4/2))_(i)(CH₂CH₂)_(j)  (II);wherein R⁵, R⁶ and R⁷ are independently H or a substituted orunsubstituted mono-valent hydrocarbon group, wherein each of R⁵ is thesame with or different from each other, each of R⁶ is the same with ordifferent from each other, f>0, g>0, h≧0, i≧0, j≧0, and the amount ofcomponent (C) is about 1 parts by weight to about 300 parts by weight,based on 100 parts by weight of the total amount of components (A) and(B); and (D) a catalyst.
 2. The curable composition of claim 1, whereinR″ is C₁-C₃alkyl or aryl group.
 3. The curable composition of claim 2,wherein R″ is methyl or phenyl.
 4. The curable composition of claim 1,wherein the component (A) is selected from:

and a combination thereof, wherein the repeated units, X, T, X′ and T′are distributed in a random manner or in an alternative manner; X is

X′ is

T is

T′ is

R″ is defined in claim 1; p is an integer ranging from 1 to 4 and eachof p is the same with or different from each other; q is an integerranging from 1 to 4 and each of q is the same with or different fromeach other; r is an integer ranging from 1 to 3; and t is an integerranging from 0 to 50 and each of t is the same with or different fromeach other.
 5. The curable composition of claim 4, wherein about atleast 10 percent by mole of R″ are aryl groups, based on the totalamount of R″.
 6. The curable composition of claim 4, wherein r is
 1. 7.The curable composition of claim 6, wherein the component (A) has thefollowing formula:

wherein X, T, R″, p and q are as defined in claim 4, t₁ and t₂ areindependently an integer ranging from 0 to 30 and t₁+t₂ ranges from 0 to50.
 8. The curable composition of claim 7 for use as a packagingmaterial for light emitting diodes.
 9. The curable composition of claim4 for use as a packaging material for light emitting diodes.
 10. Thecurable composition of claim 1, wherein component (A) is prepared by anaddition reaction.
 11. The curable composition of claim 1, whereincomponent (B) has at least one silicon-bonded alkenyl group and at leastone silicon-bonded aryl group.
 12. The curable composition of claim 1,wherein about at least 10 percent by mole of R⁴ are aryl groups, basedon the total amount of R⁴.
 13. The curable composition of claim 1,wherein component (B) has an average unit formula (V):(R⁴SiO_(3/2))_(k)[(CH₂═CH)(R⁸)₂SiO_(1/2)]_(1-k)  (V), wherein R⁴ is asdefined in claim 1, R⁸ is a substituted or unsubstituted mono-valenthydrocarbon group, each of R⁸ is the same with or different from eachother, and k ranges from about 0.5 to about 0.95.
 14. The curablecomposition of claim 13, wherein R⁴ is an aryl group or C₁-C₃ alkyl, andR⁸ is an aryl group or C₁-C₈ alkyl.
 15. The curable composition of claim1, wherein component (B) has an average unit formula (VI):(R⁴SiO_(3/2))_(x)(SiO_(4/2))_(y)[(R⁹)₃SiO_(1/2)]_(1-x-y)  (VI), whereinR⁴ is as defined in claim 1, R⁹ is a substituted or unsubstitutedmono-valent hydrocarbon group selected from aryl, C₁-C₈ alkyl and C₂-C₈alkenyl, each of R⁹ is the same with or different from each other, x>0,y>0, and x+y ranges from about 0.35 to about 0.85 and wherein about 0.1percent to about 40 percent by mole of R⁹ is C₂-C₈ alkenyl.
 16. Thecurable composition of claim 15, wherein R⁴ is an aryl group or C₁-C₃alkyl.
 17. The curable composition of claim 1, wherein the amount ofcomponent (B) is about 200 parts by weight to about 3000 parts byweight, based on 100 parts by weight of component (A).
 18. The curablecomposition of claim 17, wherein the amount of component (B) is about300 parts by weight to about 2500 parts by weight, based on 100 parts byweight of component (A).
 19. The curable composition of claim 1, whereinabout 0.1 percent by mole to about 50 percent by mole of R⁵, R⁶ and R⁷are H, and at least about 10 percent by mole of R⁵, R⁶ and R⁷ are arylgroups, based on the total amount of R⁵, R⁶ and R⁷.
 20. The curablecomposition of claim 1, wherein: f is an integer ranging from about 1 toabout 50; g is an integer ranging from about 1 to about 50; h is aninteger ranging from 0 to about 10; i is an integer ranging from 0 toabout 5; and j is an integer ranging from 0 to about
 30. 21. The curablecomposition of claim 1, wherein the amount of component (C) is about 10parts by weight to about 250 parts by weight, based on 100 parts byweight of the total amount of components (A) and (B).
 22. The curablecomposition of claim 21, wherein the amount of component (C) is about 15parts by weight to about 200 parts by weight, based on 100 parts byweight of the total amount of components (A) and (B).
 23. The curablecomposition of claim 1, wherein the catalyst of component (D) isselected from the following group: Pt, Rh, Pd, compounds and complexesof the above, and combinations thereof.
 24. The curable composition ofclaim 1 for use as a packaging material for light emitting diodes.
 25. Asemiconductor device, in which semiconductor elements are coated with acured product of the curable composition according to claim
 1. 26. Thesemiconductor device according to claim 25, wherein the semiconductorelements are light emitting diodes or light sensors.